Question: Solve for $r$ : $12 + r = -2$
Subtract $12$ from both sides: $ \begin{eqnarray} \\ 12 + r &=& -2 \\ \\ {-12} && {-12} \end{eqnarray} $ $ \begin{eqnarray} \hphantom{12 + r} &\hphantom{=}& \hphantom{-2} \\ r &=& -2 {- 12} \\ \end{eqnarray} $ Simplify. $ r = -14$